Experimental investigation on the stress sensitivity of permeability in naturally fractured shale
- 74 Downloads
In this paper, we present an experimental investigation regarding the stress sensitivity of permeability in naturally fractured shale. Gas permeability tests were performed on the fractured cylindrical shale samples under loading and unloading conditions. Different hydrostatic stress and gas pressure levels were chosen to investigate the dependence of permeability on stress. The permeability of the fractured shale decreases with increasing hydrostatic stress, re-increases during unloading and is irreversible during loading and unloading processes. The gas pressure exhibits a significant effect on the permeability in comparison with the hydrostatic stress. Small gas pressure changes (e.g., 2 MPa) induce a comparable change in permeability with a large hydrostatic stress change (e.g., 40 MPa). The gas pressure gradient on the permeability will be discussed. The fracture aperture was estimated by recording the volume change during loading and shows that the aperture change is consistent with the permeability evolution during loading, which is more complicated at a higher hydrostatic stress value. The roughness of the fractured surface was also analyzed and will be discussed in combination with the permeability evolution.
KeywordsStress sensitivity Permeability Naturally fractured shale Pore pressure Steady state method 3D scanning
The authors gratefully acknowledge the support of the National Natural Science Foundation of China (Grant nos. 41572290, 51479190 and 51879260), the Chinese Fundamental Research (973) Program (Grant no. 2015CB057906), Youth Innovation Promotion Association CAS and Hubei Provincial Natural Science Foundation of China (Grant no. 2018CFA012). These financial supports are gratefully acknowledged.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no competing financial interest.
- Lu Z, Wu X, Hu Z, Xian S, Fang R (2018b) Electric resistance tests on compacted clay material under dynamic load coupled with dry-wet cycling, Adv Mater Sci Eng 5:387–540Google Scholar
- Ren Y, Qian B, Zhang J et al (2015) Practice and understanding of industrial fracturing for shale gas of Longmaxi Formation in Changning region (in Chinese). Oil Drill Product Technol 37(4):96–99Google Scholar
- Sahimi M (1995) Flow and transport in porous media and fractured rock. VCH, VancouverGoogle Scholar
- Seidle JP, Jeansonne MW, Erickson DJ (1992) Application of matchstick geometry to stress dependent permeability in coals. In: SPE rocky mountain regional meeting, Society of petroleum engineers, Casper, Wyoming, 18–21 May 1992Google Scholar
- Su K, Sanz Perl Y, Onaisi A, Pourpark H, Vidal-Gilbert S (2017) Experimental study of hydromechanical behavior of fracture of Vaca Muerta Gas Shale, ARMA 2017-857, June 2017Google Scholar
- Ye Z, Janis M, Ghassemi A, Riley S (2017) Laboratory investigation of fluid flow and permeability evolution through shale fractures. In: Unconventional Resources Technology Conference, Austin, Texas. Society of Exploration Geophysicists, American Association of Petroleum Geologists, Society of Petroleum Engineers, 24–26 July 2017 (pp. 2038–2052)Google Scholar